A technique for in vitro secretion of androgenic sex hormone (AH) from the androgenic gland (AG) of fresh water male prawn in a defined culture medium is disclosed. AH finds use in the manipulation of the reproductive processes of prawns and shrimp for the production of sex-skewed or mono-sex progeny.
Sexual differentiation and gametogenesis in the decapods, marine shrimp (genus Penaeus) and freshwater prawns (genus Macrobrachium), occurs, respectively, in the anatomically separate testes and Androgenic Hormone (AH)-producing Androgenic Gland (AG).
Nagamine et al. (1980b) Gen. Comp. Endocrin. 41:423-441 partially sex-reversed genetic male decapods (prawns) to phenotypic females by AG ablation. This was subsequently confirmed by Sagi and Cohen (1991). Nagamine et al. (1980a) Gen. Comp. Endocrin. 41:442-457 partially sex-reversed genetic female prawns to xe2x80x9cneomalesxe2x80x9d by AG implantation. Malecha et al. (1992a) Aquaculture 105:1-18 extended this work to smaller female recipients and achieved sex-reversal by AG implantation such that neomales produced skewed sex ratio, predominantly female, progeny when mated with normal females.
The surgical implantation of AG tissue in genetic females to produce neomales is time consuming, tedious, and is not amenable to large-scale practices. Accordingly, it is an object of the present invention to provide isolated shrimp or prawn AH. It is also an object to provide methods for use of AH in the production of neomales from genetic females and sex-skewed or mono-sex shrimp or prawn progeny, therefrom.
In accordance with the foregoing object, the present invention provides an isolated shrimp or prawn androgenic polypeptide and methods of use.
Accordingly, the invention provides neomale shrimp and prawns which do not contain transplanted androgenic gland tissue.
In another aspect, the invention provides methods of producing neomale shrimp and prawns.
In yet another aspect, the invention provides methods of producing a population of shrimp and prawns having a skewed percentage in favor of females to males.
In a further aspect, the invention provides a method of identifying an agent that binds or modulates the biological activity of an androgenic polypeptide of shrimp or prawns. Accordingly, the invention provides agents that bind to or modulate an androgenic polypeptide of a shrimp or protein.
Other embodiments or aspects of the invention will become apparent to the skilled artisan by the following description of the invention.